PAPUA New Guinea's parliament has voted in favour of extending a ban on votes of no confidence from 18 months to 30 months after a government is elected.

The bill passed the first of two votes in PNG's parliament on Tuesday by 102 to nil after Prime Minister Peter O'Neill secured the support of the opposition.

The extension of the grace period, aimed at stabilising PNG's sometimes rocky politics, will become law if it passes a second vote scheduled for February 5.

"Constant shifting of loyalty in parliament means governments are planning for survival, rather than implementing policies to bring real change for our people," Mr O'Neill said on Tuesday.

"It's no wonder our health and social indicators have been in decline, and infrastructure like roads and bridges and ports are in (an) appalling state, our schools and education facilities are run down.

"We cannot allow this to continue."

AAP understands Mr O'Neill needs a vote of 74 to pass the bill into law.

Opposition leader Belden Namah, a former deputy prime minister of Mr O'Neill's, said the first stage of the bill's passage was significant.

"We have to do what is right and good for our country to suit our times," the Port Moresby-based The National Newspaper quoted him as saying.

"We cannot measure performance in 18 months ... if there is a need, we can change it to five years."

PNG parliamentarians are elected for five-year terms.

Votes of no confidence have been a thorn in the side of successive prime ministers since PNG gained independence from Australia in 1975.

PNG's first prime minister, Sir Michael Somare, lost the top job in 1980 following a vote of no confidence.

In 2003-04, the Somare government failed in its bid to have the so-called grace period extended from 18 to 36 months.

He was PNG's longest-serving prime minister after a nine-year run, but was deposed by parliament on August 2, 2011, in favour of Mr O'Neill.

That move sparked a constitutional crisis that ended in mid-2012 following a general election which put Mr O'Neill back in the prime minister's seat with the backing of about 94 of PNG's 111 MPs.

Mr O'Neill is expected to deliver a speech to the National Press Club in Canberra at 12.30 (AEDT) on Wednesday.

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